1. Field Of The Invention
The present invention relates to an inspection scaffold of large components for a boiler and a building method thereof, and particularly relates to the inspection scaffold and the building method thereof to perform pressure tests and the other inspection works of boiler superheater coils placed at a thermal power station.
2. Description of Related Art
Generally, a steam generating equipment of a thermal power station includes a burner, a furnace, a pendant coil group such as a superheater and a reheater, and these are stored inside of a large building. In such a facility, the pendant coils such as the superheater and the reheater are positioned at an upper portion of a boiler, and they are suspended and supported by a main-beam positioned particularly at a top end surface of a steel frame structure constituting a power station building. An assembling construction method is adopted for equipments including particularly a coil to be a steam passage positioned at the upper portion of the boiler such as the superheater, in which they are assembled at a factory and so on by each equipment, carried in the steel frame, lifted by each equipment by using a lifting equipment to suspend and fix to the main-beam, disposed and equipped at a predetermined position, and thereafter assembly items are assembled with each other. After the assembling of power generating equipments is completed finally, a hydraulic test is performed by passing water. Herewith, it is necessary to perform defect inspections and repair works of welded portions of the coil, and therefore, the inspection works at every portion of the coil are required. Consequently, the inspection scaffold of a large component such as the superheater is assembled, and it is a temporary scaffold which is removed after predetermined tests and inspections are finished.
The above-stated conventional inspection scaffold is used for the test after the facility is settled, and therefore, it is attached after the power station equipments are assembled. Consequently, the scaffold is assembled and attached around the coil by a high-place work at dozens of meters upward because the large components such as the superheater including these coils are positioned at a high place at the upper portion of the boiler.
As such kind of scaffold, for example, a scaffold described in Patent Document 1 is used. A suspended scaffold described in this Patent Document 1 is suspended from a boiler main body structure, having a horizontal rigid member to be the scaffold at a top layer, the scaffold of a second layer is composed of two pairs or more of perpendicular rods coupled attachably/detachably to the corresponding horizontal rigid member, horizontal rods provided with flanges at both ends and bridged attachably/detachably between the above-stated paired perpendicular rods,. and a scaffold board bridged between the corresponding horizontal rods, the scaffold of a third layer or later is composed of the perpendicular rods, the horizontal rods and the scaffold boards as same as the second layer, and it is the suspended scaffold within a boiler furnace in which the perpendicular rods are attachably/detachably suspended to the horizontal rods of an upper layer. The above-stated scaffold is provided on a wall surface around a peripheral surface inside of the boiler furnace, and it is assembled around the coil at a high place by the same method.
However, conventionally, as stated above, the building of the scaffold is a high-place work and the scaffold is built after the power station facility is assembled. Consequently, components other than the coil being an inspection object are existing around the coil, and therefore, there is a problem that the assembling work of the scaffold is very difficult. In particular, in the superheater, a lot of narrow coils are coupled to headers, this is vertically disposed in a structure well-ordered in a plane state, and equipped in a lot of lines with narrow intervals, and therefore, there are also problems that the work for the scaffold assembling is difficult and the time required for the assembling is extremely long.
[Patent Document 1] Japanese Patent Application Laid-open No. Sho 59-044504